President Obama honored the nation's fallen Monday by pointing out that this is the first Memorial Day since the end of combat operations in Afghanistan — and the first Memorial Day since 9/11 in which the United States is not involved in a major ground war.

"Most Americans don't fully see — don't fully understand — the sacrifice made by the 1% who serve in this all-volunteer armed forces," Obama said during the annual Memorial Day ceremony at Arlington National Cemetery.

He added: "A sacrifice that preserves the freedoms we too often take for granted."

Obama spotlighted the careers of the last two Americans to die in combat in Afghanistan — Wyatt Martin and Ramon Morris — and said the nation will never stop trying to repay the debt owed to these and thousands of others who made the ultimate sacrifice on behalf of the United States. The Americans who rest in the "sacred ground" at Arlington cemetery "are why our nation endures," he said.

The cemetery — "the final resting place of heroes" — is also "a reflection of America itself," Obama said. "It's a reflection of our history — the wars we've waged for democracy, the peace we've laid to preserve it."

Earlier in the ceremony, as is custom, Obama placed a wreath at the Tomb of the Unknowns.

There were once more than 100,000 troops in Afghanistan, Obama said, but that number is now below 10,000 servicemembers who train Afghan security forces. The president said that United States would continue to reduce that number and have no more than an "embassy presence" in Afghanistan by the end of next year.

"On this day, we honor the sacrifice of the thousands of American servicemembers — men and women — who gave their lives since 9/11, including more than 2,200 American patriots who made the ultimate sacrifice in Afghanistan," Obama said.

While combat operations in Afghanistan and Iraq have ended, Obama pointed out that thousands of men and women "still stand watch" across the world.

In his remarks, Obama did not mention current challenges facing the U.S. military, including its role in the regional battle against the Islamic State in Iraq and Syria. Instead, the president focused on the heroism of Americans who have fought the nation's wars, from the Civil War and World War II to Korea and Vietnam to the recent conflicts in "the deserts of the Middle East."

The nature of war has changed in the past century-and-a-half, but the values that drive the American military have not, Obama said.

"Honor ... courage ... selflessness," he said. "Those values lived in the hearts of everyday heroes who risked everything for us in every American war — men and women who now rest forever in these quiet fields and across our land."